private MessageDispatch Dequeue()

in src/main/csharp/MessageConsumer.cs [549:624]
64 lines of code
14 McCabe index (conditional complexity)

        private MessageDispatch Dequeue(TimeSpan timeout)
        {
            DateTime deadline = DateTime.Now;

            if(timeout > TimeSpan.Zero)
            {
                deadline += timeout;
            }

            while(true)
            {
                MessageDispatch dispatch = this.unconsumedMessages.Dequeue(timeout);

                // Grab a single date/time for calculations to avoid timing errors.
                DateTime dispatchTime = DateTime.Now;

                if(dispatch == null)
                {
                    if(timeout > TimeSpan.Zero && !this.unconsumedMessages.Closed)
                    {
                        if(dispatchTime > deadline)
                        {
                            // Out of time.
                            timeout = TimeSpan.Zero;
                        }
                        else
                        {
                            // Adjust the timeout to the remaining time.
                            timeout = deadline - dispatchTime;
                        }
                    }
                    else
                    {
                        if(this.failureError != null)
                        {
                            throw NMSExceptionSupport.Create(FailureError);
                        }
                        else
                        {
                            return null;
                        }
                    }
                }
                else if(dispatch.Message == null)
                {
                    return null;
                }
				else if(!IgnoreExpiration && dispatch.Message.IsExpired())
                {
                    Tracer.DebugFormat("{0} received expired message: {1}", info.ConsumerId, dispatch.Message.MessageId);

                    BeforeMessageIsConsumed(dispatch);
                    AfterMessageIsConsumed(dispatch, true);
                    // Refresh the dispatch time
                    dispatchTime = DateTime.Now;

                    if(timeout > TimeSpan.Zero && !this.unconsumedMessages.Closed)
                    {
                        if(dispatchTime > deadline)
                        {
                            // Out of time.
                            timeout = TimeSpan.Zero;
                        }
                        else
                        {
                            // Adjust the timeout to the remaining time.
                            timeout = deadline - dispatchTime;
                        }
                    }
                }
                else
                {
                    return dispatch;
                }
            }
        }